When looking for a calibration gas supplier or a supplier of specialty gases in general, it is important to understand not only what to look for in the supplier but also in the gases themselves. Of course, there are misconceptions surrounding calibration gases and specialty gases, but a quick review of what they are will ensure that they are being used properly and that you are actually using a supplier who can work with you. Having a well calibrated and specialty gas supplier in place will ensure that you are up to date and can budget properly for your actual needs.
A calibration gas is a gas mixture or reference gas used as a comparison standard in the calibration of analytical instruments, such as gas analyzers or gas detectors. Therefore, the calibration gas must have a precisely defined nature or composition, such as zero gas or span gas, for example 500 ppm carbon monoxide in nitrogen
Obviously, calibration gases are not the only specialty gases on the market. Specialty gases have a number of different applications, and with them come different types of specialty gas equipment as well as different applications. As specialty gases of extremely high purity, i.e. 99.995% are used in many industries and have applications including pharmaceuticals, semiconductors, medicine, electronics, petrochemicals and aviation . Of course, this does not mean that these gases can only be used strictly in these industries. However, they are certainly the main application and market categories that specialty gases are divided into.
Traceability of calibration gas
To become a calibration gas, the gas must be traceable to national or international standards. Traceability is an unbroken chain of comparisons with an internationally accepted standard. Calibration gas standards establish a known analyzer response to a certified chemical component concentration. In calibration gases, preparation tolerance (PT) and certification/analytical accuracy (CA) are extremely important.
Tolerance of calibration gas
A formulation tolerance is a concentration range that includes additives and concentrations. PT is measured over a concentration range. It can also be called blend tolerance. For example, a nitrogen-balanced 500 ppm CO calibration gas with a PT of +/- 10% contains between 450 ppm and 550 ppm. Preparation tolerances can be minimized by using the latest technologies for the production of such gases. Preparation tolerances are decided on the basis of the manufacturer’s experience and customer requirements.
Certification of calibration gas
Analytical accuracy certification is defined as the agreement of the measured value with its true value. The certification values are determined statistically, taking into account the uncertainties associated with the international standard (reference standard) it can monitor, the uncertainty of the device and the variability determination (reactivity) of the gas in the container.
